Hello All,
Some CIS details below but have symptoms when measuring control and system pressure that I'm hoping someone can make sense of. Couldn't find a related question/reply using search.
Attempting to improve fuel delivery of my transplanted (long ago) 3.0 sc motor. When I connect my CIS gauges things seem to be measuring as expected. I measure control pressure first and then close the valve and record system pressure. The part that doesn't seem correct is the pressure doesn't drop back to control pressure once the valve is open again. Does that provide some direction in my CIS knowledge journey? The fact it didn't drop seemed wrong during my previous attempts at messing with the system, but really clicked when watching the Klassik Automotive CIS video for the thirtieth time. When Kurt switches back to control pressure and plugs in the WUR, the pressure does drop as expected.
The other puzzling bit that hadn't registered previously is that I haven't been able to remove the piston that sits at the end of the system pressure adjustment screw. I didn't have a magnet small enough to reach into the recess (do now). Felt like I got good engagement using a SAE size allen wrench but couldn't get it out. I'm guessing it shouldn't be that stubborn. Related to pressure shenanigan's?
Piston that sits at the end of this screw:
Took a low res. photo down the adjustment screw bore with the borescope. Guessing there is a piston down there somewhere:
Alright, here are some of the details you need to understand my system. Sorry for putting the cart before the horse. I have read and printed out the info check list from the CIS for dummies thread (my people). The process falls apart for me when the control system pressure readings don't behave as I expect. Then I spend and hour or two attempting to get repeatability with the pressure adjustment screw using the rest of the time available.
Year of engine: 83 3.0 sc (no sump pan/plate)
WUR Model: ending in 045
FD Model : 0 438 100 031
Ambient and measured WUR surface temp: 15.5C
WUR resistance: 24.6 ohms
CCP 1: 4bar
SP 1: 6bar
I then went down the "I need to get SP in range rabbit hole repeating the process 12 times. System pressure cdid change with FD screw washer adjustments but didn't always track (more washers didn't always increase SP). Adjustments resulted in SPs ranging from 3.2 bar. (too low) to 6 bar. and CCP ranging (after adjustment from 1.8 bar to 3.4). After messing about it was time to button things up and call it a day.
I would be appreciative of any insights if the above info. is cohesive enough to guide future steps.
In a prior post I was asked to document fuel delivery rate to the engine bay. I didn't collect that data but can if still helpful.
Like I said in a different post, I'm happy to be on the journey as the car is relatively new to me. It's all part of the process in getting to know and appreciate this sweet 911.
